No, or the Vain Glory of Command

No, or the Vain Glory of Command is a 1990 Portuguese film directed by Manoel de Oliveira. Starring Luís Miguel Cintra and Miguel Guilherme, the film portrays a series of defeats in Portuguese military history—such as the assassination of Viriathus, the Battle of Toro, the failed attempt at Iberian Union under Afonso of Portugal and Isabella of Spain, and the Battle of Alcácer Quibir. Additionally, it includes the episode of the Island of Love from The Lusiads. These events are recounted through flashbacks as a Portuguese lieutenant, stationed in an African territory during the Portuguese Colonial War (1961–74), narrates them while marching in 1974. He effortlessly draws his comrades into philosophical discussions, even as their small contingent endures surprise attacks from independence guerrillas.

Synopsis from Wikipedia, CC BY-SA 4.0. Everything below written here.